I flip-flop between Tweetie2, SimplyTweet, and Twittelator. T2 is fast, and I like the UI for the most part. ST is close, but I get connection popups a lot more than the other apps, and I wish there was more than just 3 choices for the "swipe" menu. Twittelator has a lot of features, but it just doesn't flow as well for me as the other two. It is a nice client, though.